You need the diff, and a shim kit so you can shim the front and rear outdrive pinion in those diffs while your at it. Your diff fluid about 50,000wt for the center and 20,000 to 30,000 for the front and rear diffs. This will set you back about $60. If you talk to annie_ himself you should be able to get some details about the conversion. I have all the parts on order so I havent dug into the one I'm repairing for a friend. When all is said and done you will be spending more than you would for a CRT, LSP and I would not get the Hellfire until it's been out for a while but that's just my opinion. Good luck. From what I can tell you have to use XTM parts cause I tried diffs from 5 different makers and none would work without some remodeling.